oracle Oracle全文，CONTAINS()的语法
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Oracle full text, the syntax of CONTAINS()
提问by gfytd
contains(columnname, 'ABC')=0
this means search for the data which doesn't contain word 'ABC'
这意味着搜索不包含单词“ABC”的数据
contains(columnname, 'ABC and XYZ')=0
contains(columnname, 'ABC or XYZ')=0
what do these 2 sql mean? I tested them, there's no syntax error, but they didn't work as I expected, the 'and' seems like an 'or', and 'or' seems like an 'and', could anyone help to explain this? all doc found in google are for contains()>0, those're not what I need.
这两个sql是什么意思？我测试了它们，没有语法错误，但它们没有按我预期的那样工作，'and' 看起来像一个 'or'，而 'or' 看起来像一个 'and'，谁能帮忙解释一下？在 google 中找到的所有文档都用于 contains()>0，那些不是我需要的。
thanks in advance.
提前致谢。
回答by A.B.Cade
According to oracle documentation, the containsfunction :
根据oracle文档，该contains功能：
returns a relevance score for every row selected
为选定的每一行返回相关性分数
If you ask for
如果你要求
contains(columnname, 'ABC')=0
You actually ask for a score of 0which means: columnname doesn't contain 'ABC'
您实际上要求得分，0这意味着：列名不包含“ABC”
According to the docs:
根据文档：
In an AND query, the score returned is the score of the lowest query term
In an OR query, the score returned is the score for the highest query term
在 AND 查询中，返回的分数是最低查询词的分数
在 OR 查询中，返回的分数是最高查询词的分数
So if you ask for:
所以如果你要求：
contains(columnname, 'ABC and XYZ')=0
then if either 'ABC' or'XYZ' has a score of 0it will have the lowest score and that's what you'll get from the function, so you're actually asking for: columnname doesn't contain 'ABC' or 'XYZ' (at least one of them).
那么如果“ABC”或“XYZ”的得分0最低，这就是你从函数中得到的，所以你实际上是在要求：列名不包含“ABC”或“XYZ” '（至少其中之一）。
Same thing for the or-
同样的事情 or-
contains(columnname, 'ABC or XYZ')=0
only if both 'ABC' and'XYZ' have the score of 0the function will return 0, so you're actually asking for: columnname doesn't contain 'ABC' and 'XYZ' (both of them).
仅当 'ABC'和'XYZ' 都具有该0函数的分数时才会返回0，所以您实际上是在要求： columnname 不包含 'ABC' 和 'XYZ'（两者）。
IMHO, this behaviour is correct since it meets De-Moragan's Laws
恕我直言，这种行为是正确的，因为它符合德莫拉根定律
